Measurement of Small Specific Contact Resistance of Metals with Resistive Semiconductors

Abstract

The method to measure specific contact resistance of metals with resistive semiconductors has difficulties associated with it. These difficulties are discussed in relation to contacts on gallium nitride (GaN). The specific contact resistance of a Ni/Au contact on p-GaN after oxygen anneal was determined to be on the order of 10 )1 Wcm 2 , which is significantly higher than the best value (10 )6 Wcm 2 ) reported in the literature. However, the basic measurement of current-voltage (I-V) characteristics of the contact in determining the specific contact resistance is not significantly different. The analysis shows that in materials such as p-GaN, which is highly resistive, a low specific contact resistance may be difficult to measure by standard transmission line methods below approximately 10 )2 -10 )3 Wcm 2 in p-GaN.

Evaluation of metal/indium-tin-oxide for transparent low-resistance contacts to p-type GaN

“…We therefore limit our analysis of ρ c to the 1 V range. Furthermore, inaccuracies in the layer and contact geometry have a strong effect on values derived from contacts on poorly conducting layers, such as p-type GaN [17]. We therefore paid particular attention to accurately account for the actual contact geometry within 5%.…”